m-lamonaca/dev-notes
1
0
Fork 0
mirror of https://github.com/m-lamonaca/dev-notes.git synced 2025-04-07 03:16:41 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions
dev-notes/languages/rust/macros.html

4499 lines
No EOL
101 KiB
HTML
Raw Permalink Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<!doctype html>
<html lang="en" class="no-js">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="author" content="Marcello Lamonaca">
<link rel="canonical" href="http://m-lamonaca.github.io/dev-notes/languages/rust/macros.html">
<link rel="prev" href="rust.html">
<link rel="next" href="cargo.html">
<link rel="icon" href="../../assets/images/favicon.png">
<meta name="generator" content="mkdocs-1.6.1, mkdocs-material-9.5.34">
<title>Macros - Dev Notes</title>
<link rel="stylesheet" href="../../assets/stylesheets/main.35f28582.min.css">
<link rel="stylesheet" href="../../assets/stylesheets/palette.06af60db.min.css">
<script src="https://unpkg.com/iframe-worker/shim"></script>
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback">
<style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style>
<script>__md_scope=new URL("../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script>
<meta property="og:type" content="website" >
<meta property="og:title" content="Macros - Dev Notes" >
<meta property="og:description" content="None" >
<meta property="og:image" content="http://m-lamonaca.github.io/dev-notes/assets/images/social/languages/rust/macros.png" >
<meta property="og:image:type" content="image/png" >
<meta property="og:image:width" content="1200" >
<meta property="og:image:height" content="630" >
<meta property="og:url" content="http://m-lamonaca.github.io/dev-notes/languages/rust/macros.html" >
<meta name="twitter:card" content="summary_large_image" >
<meta name="twitter:title" content="Macros - Dev Notes" >
<meta name="twitter:description" content="None" >
<meta name="twitter:image" content="http://m-lamonaca.github.io/dev-notes/assets/images/social/languages/rust/macros.png" >
</head>
<body dir="ltr" data-md-color-scheme="default" data-md-color-primary="orange" data-md-color-accent="deep-orange">
<input class="md-toggle" data-md-toggle="drawer" type="checkbox" id="__drawer" autocomplete="off">
<input class="md-toggle" data-md-toggle="search" type="checkbox" id="__search" autocomplete="off">
<label class="md-overlay" for="__drawer"></label>
<div data-md-component="skip">
<a href="#macros" class="md-skip">
Skip to content
</a>
</div>
<div data-md-component="announce">
</div>
<header class="md-header md-header--shadow md-header--lifted" data-md-component="header">
<nav class="md-header__inner md-grid" aria-label="Header">
<a href="../../index.html" title="Dev Notes" class="md-header__button md-logo" aria-label="Dev Notes" data-md-component="logo">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M392.8 1.2c-17-4.9-34.7 5-39.6 22l-128 448c-4.9 17 5 34.7 22 39.6s34.7-5 39.6-22l128-448c4.9-17-5-34.7-22-39.6m80.6 120.1c-12.5 12.5-12.5 32.8 0 45.3l89.3 89.4-89.4 89.4c-12.5 12.5-12.5 32.8 0 45.3s32.8 12.5 45.3 0l112-112c12.5-12.5 12.5-32.8 0-45.3l-112-112c-12.5-12.5-32.8-12.5-45.3 0zm-306.7 0c-12.5-12.5-32.8-12.5-45.3 0l-112 112c-12.5 12.5-12.5 32.8 0 45.3l112 112c12.5 12.5 32.8 12.5 45.3 0s12.5-32.8 0-45.3L77.3 256l89.4-89.4c12.5-12.5 12.5-32.8 0-45.3"/></svg>
</a>
<label class="md-header__button md-icon" for="__drawer">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg>
</label>
<div class="md-header__title" data-md-component="header-title">
<div class="md-header__ellipsis">
<div class="md-header__topic">
<span class="md-ellipsis">
Dev Notes
</span>
</div>
<div class="md-header__topic" data-md-component="header-topic">
<span class="md-ellipsis">
Macros
</span>
</div>
</div>
</div>
<form class="md-header__option" data-md-component="palette">
<input class="md-option" data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme="default" data-md-color-primary="orange" data-md-color-accent="deep-orange" aria-label="Switch to dark mode" type="radio" name="__palette" id="__palette_0">
<label class="md-header__button md-icon" title="Switch to dark mode" for="__palette_1" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg>
</label>
<input class="md-option" data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme="slate" data-md-color-primary="orange" data-md-color-accent="deep-orange" aria-label="Switch to light mode" type="radio" name="__palette" id="__palette_1">
<label class="md-header__button md-icon" title="Switch to light mode" for="__palette_0" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg>
</label>
</form>
<script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script>
<label class="md-header__button md-icon" for="__search">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg>
</label>
<div class="md-search" data-md-component="search" role="dialog">
<label class="md-search__overlay" for="__search"></label>
<div class="md-search__inner" role="search">
<form class="md-search__form" name="search">
<input type="text" class="md-search__input" name="query" aria-label="Search" placeholder="Search" autocapitalize="off" autocorrect="off" autocomplete="off" spellcheck="false" data-md-component="search-query" required>
<label class="md-search__icon md-icon" for="__search">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11z"/></svg>
</label>
<nav class="md-search__options" aria-label="Search">
<button type="reset" class="md-search__icon md-icon" title="Clear" aria-label="Clear" tabindex="-1">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M19 6.41 17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z"/></svg>
</button>
</nav>
</form>
<div class="md-search__output">
<div class="md-search__scrollwrap" tabindex="0" data-md-scrollfix>
<div class="md-search-result" data-md-component="search-result">
<div class="md-search-result__meta">
Initializing search
</div>
<ol class="md-search-result__list" role="presentation"></ol>
</div>
</div>
</div>
</div>
</div>
<div class="md-header__source">
<a href="https://github.com/m-lamonaca/dev-notes" title="Go to repository" class="md-source" data-md-component="source">
<div class="md-source__icon md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81"/></svg>
</div>
<div class="md-source__repository">
GitHub
</div>
</a>
</div>
</nav>
<nav class="md-tabs" aria-label="Tabs" data-md-component="tabs">
<div class="md-grid">
<ul class="md-tabs__list">
<li class="md-tabs__item">
<a href="../../index.html" class="md-tabs__link">
Home
</a>
</li>
<li class="md-tabs__item">
<a href="../../containers/docker.html" class="md-tabs__link">
Containers
</a>
</li>
<li class="md-tabs__item">
<a href="../../databases/redis.html" class="md-tabs__link">
Databases
</a>
</li>
<li class="md-tabs__item md-tabs__item--active">
<a href="../html/html.html" class="md-tabs__link">
Languages
</a>
</li>
<li class="md-tabs__item">
<a href="../../misc/git.html" class="md-tabs__link">
Misc
</a>
</li>
<li class="md-tabs__item">
<a href="../../linux/filesystem/file-links.html" class="md-tabs__link">
Linux
</a>
</li>
</ul>
</div>
</nav>
</header>
<div class="md-container" data-md-component="container">
<main class="md-main" data-md-component="main">
<div class="md-main__inner md-grid">
<div class="md-sidebar md-sidebar--primary" data-md-component="sidebar" data-md-type="navigation" >
<div class="md-sidebar__scrollwrap">
<div class="md-sidebar__inner">
<nav class="md-nav md-nav--primary md-nav--lifted" aria-label="Navigation" data-md-level="0">
<label class="md-nav__title" for="__drawer">
<a href="../../index.html" title="Dev Notes" class="md-nav__button md-logo" aria-label="Dev Notes" data-md-component="logo">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M392.8 1.2c-17-4.9-34.7 5-39.6 22l-128 448c-4.9 17 5 34.7 22 39.6s34.7-5 39.6-22l128-448c4.9-17-5-34.7-22-39.6m80.6 120.1c-12.5 12.5-12.5 32.8 0 45.3l89.3 89.4-89.4 89.4c-12.5 12.5-12.5 32.8 0 45.3s32.8 12.5 45.3 0l112-112c12.5-12.5 12.5-32.8 0-45.3l-112-112c-12.5-12.5-32.8-12.5-45.3 0zm-306.7 0c-12.5-12.5-32.8-12.5-45.3 0l-112 112c-12.5 12.5-12.5 32.8 0 45.3l112 112c12.5 12.5 32.8 12.5 45.3 0s12.5-32.8 0-45.3L77.3 256l89.4-89.4c12.5-12.5 12.5-32.8 0-45.3"/></svg>
</a>
Dev Notes
</label>
<div class="md-nav__source">
<a href="https://github.com/m-lamonaca/dev-notes" title="Go to repository" class="md-source" data-md-component="source">
<div class="md-source__icon md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81"/></svg>
</div>
<div class="md-source__repository">
GitHub
</div>
</a>
</div>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../index.html" class="md-nav__link">
<span class="md-ellipsis">
Home
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_2" >
<label class="md-nav__link" for="__nav_2" id="__nav_2_label" tabindex="0">
<span class="md-ellipsis">
Containers
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_2">
<span class="md-nav__icon md-icon"></span>
Containers
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../containers/docker.html" class="md-nav__link">
<span class="md-ellipsis">
Docker
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../containers/kubernetes.html" class="md-nav__link">
<span class="md-ellipsis">
Kubernetes
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3" >
<label class="md-nav__link" for="__nav_3" id="__nav_3_label" tabindex="0">
<span class="md-ellipsis">
Databases
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_3_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3">
<span class="md-nav__icon md-icon"></span>
Databases
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../databases/redis.html" class="md-nav__link">
<span class="md-ellipsis">
Redis
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../databases/sql.html" class="md-nav__link">
<span class="md-ellipsis">
SQL
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../databases/mongo-db.html" class="md-nav__link">
<span class="md-ellipsis">
MongoDB
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--active md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" checked>
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="">
<span class="md-ellipsis">
Languages
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="true">
<label class="md-nav__title" for="__nav_4">
<span class="md-nav__icon md-icon"></span>
Languages
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../html/html.html" class="md-nav__link">
<span class="md-ellipsis">
HTML
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../markdown.html" class="md-nav__link">
<span class="md-ellipsis">
Markdown
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../css/css.html" class="md-nav__link">
<span class="md-ellipsis">
CSS
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../c/c.html" class="md-nav__link">
<span class="md-ellipsis">
C
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../kotlin/kotlin.html" class="md-nav__link">
<span class="md-ellipsis">
Kotlin
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../swift/swift.html" class="md-nav__link">
<span class="md-ellipsis">
Swift
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_7" >
<label class="md-nav__link" for="__nav_4_7" id="__nav_4_7_label" tabindex="">
<span class="md-ellipsis">
Assembly
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_7_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_7">
<span class="md-nav__icon md-icon"></span>
Assembly
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../assembly/intel.html" class="md-nav__link">
<span class="md-ellipsis">
Intel
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../assembly/riscv.html" class="md-nav__link">
<span class="md-ellipsis">
RISC-V
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_8" >
<label class="md-nav__link" for="__nav_4_8" id="__nav_4_8_label" tabindex="">
<span class="md-ellipsis">
Python
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_8_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_8">
<span class="md-nav__icon md-icon"></span>
Python
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../python/python.html" class="md-nav__link">
<span class="md-ellipsis">
Python
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_8_2" >
<label class="md-nav__link" for="__nav_4_8_2" id="__nav_4_8_2_label" tabindex="0">
<span class="md-ellipsis">
Modules
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_8_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_8_2">
<span class="md-nav__icon md-icon"></span>
Modules
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../python/modules/argparse.html" class="md-nav__link">
<span class="md-ellipsis">
argparse
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/collections.html" class="md-nav__link">
<span class="md-ellipsis">
collection
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/csv.html" class="md-nav__link">
<span class="md-ellipsis">
csv
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/ftplib.html" class="md-nav__link">
<span class="md-ellipsis">
ftplib
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/itertools.html" class="md-nav__link">
<span class="md-ellipsis">
itertools
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/json.html" class="md-nav__link">
<span class="md-ellipsis">
json
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/logging.html" class="md-nav__link">
<span class="md-ellipsis">
logging
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/shutil.html" class="md-nav__link">
<span class="md-ellipsis">
shutil
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/smtplib.html" class="md-nav__link">
<span class="md-ellipsis">
smtplib
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/socket.html" class="md-nav__link">
<span class="md-ellipsis">
socket
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/sqlite.html" class="md-nav__link">
<span class="md-ellipsis">
sqlite
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/time-datetime.html" class="md-nav__link">
<span class="md-ellipsis">
time & datetime
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/modules/unittest.html" class="md-nav__link">
<span class="md-ellipsis">
unittest
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_8_3" >
<label class="md-nav__link" for="__nav_4_8_3" id="__nav_4_8_3_label" tabindex="0">
<span class="md-ellipsis">
Libraries
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_8_3_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_8_3">
<span class="md-nav__icon md-icon"></span>
Libraries
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../python/libs/tkinter.html" class="md-nav__link">
<span class="md-ellipsis">
TKinter
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/libs/numpy.html" class="md-nav__link">
<span class="md-ellipsis">
Numpy
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/libs/pandas.html" class="md-nav__link">
<span class="md-ellipsis">
Pandas
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/libs/seaborn.html" class="md-nav__link">
<span class="md-ellipsis">
Seaborn
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/libs/requests.html" class="md-nav__link">
<span class="md-ellipsis">
Requests
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../python/libs/beautiful-soup.html" class="md-nav__link">
<span class="md-ellipsis">
Beatiful Soup
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_9" >
<label class="md-nav__link" for="__nav_4_9" id="__nav_4_9_label" tabindex="">
<span class="md-ellipsis">
.NET
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_9_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_9">
<span class="md-nav__icon md-icon"></span>
.NET
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_9_1" >
<label class="md-nav__link" for="__nav_4_9_1" id="__nav_4_9_1_label" tabindex="0">
<span class="md-ellipsis">
C#
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_9_1_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_9_1">
<span class="md-nav__icon md-icon"></span>
C#
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../dotnet/csharp/csharp.html" class="md-nav__link">
<span class="md-ellipsis">
C#
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/csharp/linq.html" class="md-nav__link">
<span class="md-ellipsis">
Linq
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/csharp/collections.html" class="md-nav__link">
<span class="md-ellipsis">
Collections
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/csharp/reactive-extensions.html" class="md-nav__link">
<span class="md-ellipsis">
Reactive Extensions
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/csharp/async-programming.html" class="md-nav__link">
<span class="md-ellipsis">
Async Programming
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/csharp/unit-tests.html" class="md-nav__link">
<span class="md-ellipsis">
Unit Tests
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_9_2" >
<label class="md-nav__link" for="__nav_4_9_2" id="__nav_4_9_2_label" tabindex="0">
<span class="md-ellipsis">
ASP.NET
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_9_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_9_2">
<span class="md-nav__icon md-icon"></span>
ASP.NET
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../dotnet/asp.net/minimal-api.html" class="md-nav__link">
<span class="md-ellipsis">
Minimal API
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/asp.net/filters.html" class="md-nav__link">
<span class="md-ellipsis">
FIlters
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/asp.net/middleware.html" class="md-nav__link">
<span class="md-ellipsis">
Middleware
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/asp.net/razor-syntax.html" class="md-nav__link">
<span class="md-ellipsis">
Razor Syntax
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/asp.net/blazor.html" class="md-nav__link">
<span class="md-ellipsis">
Blazor
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/asp.net/signalr.html" class="md-nav__link">
<span class="md-ellipsis">
SignalR
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/asp.net/web-forms.html" class="md-nav__link">
<span class="md-ellipsis">
Web Forms
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_9_3" >
<label class="md-nav__link" for="__nav_4_9_3" id="__nav_4_9_3_label" tabindex="0">
<span class="md-ellipsis">
Database
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_9_3_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_9_3">
<span class="md-nav__icon md-icon"></span>
Database
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../dotnet/database/ado.net.html" class="md-nav__link">
<span class="md-ellipsis">
ADO.NET
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../dotnet/database/entity-framework.html" class="md-nav__link">
<span class="md-ellipsis">
Entity Framework
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_10" >
<label class="md-nav__link" for="__nav_4_10" id="__nav_4_10_label" tabindex="">
<span class="md-ellipsis">
Java
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_10_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_10">
<span class="md-nav__icon md-icon"></span>
Java
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../java/java.html" class="md-nav__link">
<span class="md-ellipsis">
Java
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../java/java-collection-framework.html" class="md-nav__link">
<span class="md-ellipsis">
Java Collection Framework
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../java/dao.html" class="md-nav__link">
<span class="md-ellipsis">
DAO
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_10_4" >
<label class="md-nav__link" for="__nav_4_10_4" id="__nav_4_10_4_label" tabindex="0">
<span class="md-ellipsis">
Web
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_10_4_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_10_4">
<span class="md-nav__icon md-icon"></span>
Web
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../java/web/servlet.html" class="md-nav__link">
<span class="md-ellipsis">
Serverlet
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_10_4_2" >
<label class="md-nav__link" for="__nav_4_10_4_2" id="__nav_4_10_4_2_label" tabindex="0">
<span class="md-ellipsis">
Spring
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="4" aria-labelledby="__nav_4_10_4_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_10_4_2">
<span class="md-nav__icon md-icon"></span>
Spring
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../java/spring/pom.xml.html" class="md-nav__link">
<span class="md-ellipsis">
POM
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../java/spring/spring-project.html" class="md-nav__link">
<span class="md-ellipsis">
Project Structure
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_11" >
<label class="md-nav__link" for="__nav_4_11" id="__nav_4_11_label" tabindex="">
<span class="md-ellipsis">
PHP
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_11_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_11">
<span class="md-nav__icon md-icon"></span>
PHP
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../php/php.html" class="md-nav__link">
<span class="md-ellipsis">
PHP
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/database.html" class="md-nav__link">
<span class="md-ellipsis">
Database
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/web.html" class="md-nav__link">
<span class="md-ellipsis">
Web
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/dependency-injection.html" class="md-nav__link">
<span class="md-ellipsis">
Dependency Injection
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/unit-tests.html" class="md-nav__link">
<span class="md-ellipsis">
Unit Tests
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/composer.html" class="md-nav__link">
<span class="md-ellipsis">
Composer
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/psr-7.html" class="md-nav__link">
<span class="md-ellipsis">
PSR 7
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/plates-templating.html" class="md-nav__link">
<span class="md-ellipsis">
Plates
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_11_9" >
<label class="md-nav__link" for="__nav_4_11_9" id="__nav_4_11_9_label" tabindex="0">
<span class="md-ellipsis">
Simple MVC
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_11_9_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_11_9">
<span class="md-nav__icon md-icon"></span>
Simple MVC
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../php/simple-mvc/simple-mvc.html" class="md-nav__link">
<span class="md-ellipsis">
Simple MVC
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../php/simple-mvc/rest-api.html" class="md-nav__link">
<span class="md-ellipsis">
REST API
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--active md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_12" checked>
<label class="md-nav__link" for="__nav_4_12" id="__nav_4_12_label" tabindex="">
<span class="md-ellipsis">
Rust
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_12_label" aria-expanded="true">
<label class="md-nav__title" for="__nav_4_12">
<span class="md-nav__icon md-icon"></span>
Rust
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="rust.html" class="md-nav__link">
<span class="md-ellipsis">
Rust
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--active">
<input class="md-nav__toggle md-toggle" type="checkbox" id="__toc">
<label class="md-nav__link md-nav__link--active" for="__toc">
<span class="md-ellipsis">
Macros
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<a href="macros.html" class="md-nav__link md-nav__link--active">
<span class="md-ellipsis">
Macros
</span>
</a>
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
<label class="md-nav__title" for="__toc">
<span class="md-nav__icon md-icon"></span>
Table of contents
</label>
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
<li class="md-nav__item">
<a href="#declarative-macros-macro-by-example" class="md-nav__link">
<span class="md-ellipsis">
Declarative Macros (Macro-by-Example)
</span>
</a>
<nav class="md-nav" aria-label="Declarative Macros (Macro-by-Example)">
<ul class="md-nav__list">
<li class="md-nav__item">
<a href="#transcribing" class="md-nav__link">
<span class="md-ellipsis">
Transcribing
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#metavariables" class="md-nav__link">
<span class="md-ellipsis">
Metavariables
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#repetitions" class="md-nav__link">
<span class="md-ellipsis">
Repetitions
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#scoping-exporting-and-importing" class="md-nav__link">
<span class="md-ellipsis">
Scoping, Exporting, and Importing
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#the-macro_use-attribute" class="md-nav__link">
<span class="md-ellipsis">
The macro_use attribute
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#the-macro_export-attribute" class="md-nav__link">
<span class="md-ellipsis">
The macro_export attribute
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#follow-set-ambiguity-restrictions" class="md-nav__link">
<span class="md-ellipsis">
Follow-set Ambiguity Restrictions
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="cargo.html" class="md-nav__link">
<span class="md-ellipsis">
Cargo
</span>
</a>
</li>
<li class="md-nav__item">
<a href="concurrency.html" class="md-nav__link">
<span class="md-ellipsis">
Concurrency
</span>
</a>
</li>
<li class="md-nav__item">
<a href="unit-tests.html" class="md-nav__link">
<span class="md-ellipsis">
Unit Tests
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_13" >
<label class="md-nav__link" for="__nav_4_13" id="__nav_4_13_label" tabindex="">
<span class="md-ellipsis">
Javascript
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_13_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_13">
<span class="md-nav__icon md-icon"></span>
Javascript
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../javascript/javascript.html" class="md-nav__link">
<span class="md-ellipsis">
Javascript
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/dom.html" class="md-nav__link">
<span class="md-ellipsis">
DOM
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/events-animation.html" class="md-nav__link">
<span class="md-ellipsis">
Events & Animation
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/ajax.html" class="md-nav__link">
<span class="md-ellipsis">
AJAX
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/jquery.html" class="md-nav__link">
<span class="md-ellipsis">
jQuery
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_13_6" >
<label class="md-nav__link" for="__nav_4_13_6" id="__nav_4_13_6_label" tabindex="0">
<span class="md-ellipsis">
React
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_4_13_6_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_13_6">
<span class="md-nav__icon md-icon"></span>
React
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../javascript/react/react.html" class="md-nav__link">
<span class="md-ellipsis">
React
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/react/react-router.html" class="md-nav__link">
<span class="md-ellipsis">
React Router
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/react/react-tests.html" class="md-nav__link">
<span class="md-ellipsis">
React Tests
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/react/redux.html" class="md-nav__link">
<span class="md-ellipsis">
Redux
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../javascript/react/redux-tests.html" class="md-nav__link">
<span class="md-ellipsis">
Redux Tests
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="../javascript/svelte/svelte.html" class="md-nav__link">
<span class="md-ellipsis">
Svelte
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_14" >
<label class="md-nav__link" for="__nav_4_14" id="__nav_4_14_label" tabindex="">
<span class="md-ellipsis">
PowerShell
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_14_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_14">
<span class="md-nav__icon md-icon"></span>
PowerShell
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../powershell/scripting.html" class="md-nav__link">
<span class="md-ellipsis">
Scripting
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../powershell/commands.html" class="md-nav__link">
<span class="md-ellipsis">
Commands
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4_15" >
<label class="md-nav__link" for="__nav_4_15" id="__nav_4_15_label" tabindex="">
<span class="md-ellipsis">
Bash
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_4_15_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4_15">
<span class="md-nav__icon md-icon"></span>
Bash
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../bash/scripting.html" class="md-nav__link">
<span class="md-ellipsis">
Scripting
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../bash/commands.html" class="md-nav__link">
<span class="md-ellipsis">
Commands
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_5" >
<label class="md-nav__link" for="__nav_5" id="__nav_5_label" tabindex="0">
<span class="md-ellipsis">
Misc
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_5_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_5">
<span class="md-nav__icon md-icon"></span>
Misc
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../misc/git.html" class="md-nav__link">
<span class="md-ellipsis">
Git
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../misc/graph-ql.html" class="md-nav__link">
<span class="md-ellipsis">
GraphQL
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../misc/regular-expressions.html" class="md-nav__link">
<span class="md-ellipsis">
RegEx
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../misc/ssh.html" class="md-nav__link">
<span class="md-ellipsis">
SSH
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../misc/web-components.html" class="md-nav__link">
<span class="md-ellipsis">
WebComponents
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6" >
<label class="md-nav__link" for="__nav_6" id="__nav_6_label" tabindex="0">
<span class="md-ellipsis">
Linux
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_6_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_6">
<span class="md-nav__icon md-icon"></span>
Linux
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6_1" >
<label class="md-nav__link" for="__nav_6_1" id="__nav_6_1_label" tabindex="0">
<span class="md-ellipsis">
Filesystem
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_6_1_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_6_1">
<span class="md-nav__icon md-icon"></span>
Filesystem
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../linux/filesystem/file-links.html" class="md-nav__link">
<span class="md-ellipsis">
File Links
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../linux/filesystem/procfs.html" class="md-nav__link">
<span class="md-ellipsis">
/proc
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../linux/filesystem/sysfs.html" class="md-nav__link">
<span class="md-ellipsis">
/sys
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_6_2" >
<label class="md-nav__link" for="__nav_6_2" id="__nav_6_2_label" tabindex="0">
<span class="md-ellipsis">
System Init
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_6_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_6_2">
<span class="md-nav__icon md-icon"></span>
System Init
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../linux/init/systemd.html" class="md-nav__link">
<span class="md-ellipsis">
Systemd
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../linux/init/open-rc.html" class="md-nav__link">
<span class="md-ellipsis">
OpenRC
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</div>
</div>
</div>
<div class="md-sidebar md-sidebar--secondary" data-md-component="sidebar" data-md-type="toc" >
<div class="md-sidebar__scrollwrap">
<div class="md-sidebar__inner">
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
<label class="md-nav__title" for="__toc">
<span class="md-nav__icon md-icon"></span>
Table of contents
</label>
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
<li class="md-nav__item">
<a href="#declarative-macros-macro-by-example" class="md-nav__link">
<span class="md-ellipsis">
Declarative Macros (Macro-by-Example)
</span>
</a>
<nav class="md-nav" aria-label="Declarative Macros (Macro-by-Example)">
<ul class="md-nav__list">
<li class="md-nav__item">
<a href="#transcribing" class="md-nav__link">
<span class="md-ellipsis">
Transcribing
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#metavariables" class="md-nav__link">
<span class="md-ellipsis">
Metavariables
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#repetitions" class="md-nav__link">
<span class="md-ellipsis">
Repetitions
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#scoping-exporting-and-importing" class="md-nav__link">
<span class="md-ellipsis">
Scoping, Exporting, and Importing
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#the-macro_use-attribute" class="md-nav__link">
<span class="md-ellipsis">
The macro_use attribute
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#the-macro_export-attribute" class="md-nav__link">
<span class="md-ellipsis">
The macro_export attribute
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#follow-set-ambiguity-restrictions" class="md-nav__link">
<span class="md-ellipsis">
Follow-set Ambiguity Restrictions
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</div>
</div>
</div>
<div class="md-content" data-md-component="content">
<article class="md-content__inner md-typeset">
<h1 id="macros">Macros</h1>
<p>Fundamentally, <strong>macros</strong> are a way of <em>writing code that writes other code</em>, which is known as <strong>metaprogramming</strong>.</p>
<p>Metaprogramming is useful for reducing the amount of code to be written and maintained, which is also one of the roles of functions. However, macros have some additional powers that functions don’t.</p>
<p>A function signature must declare the number and type of parameters the function has. Macros, on the other hand, can take a variable number of parameters. Also, macros are expanded before the compiler interprets the meaning of the code, so a macro can, for example, implement a trait on a given type. A function can’t, because it gets called at runtime and a trait needs to be implemented at compile time.</p>
<p>The downside to implementing a macro instead of a function is that macro definitions are more complex than function definitions because it's Rust code that writes Rust code. Due to this indirection, macro definitions are generally more difficult to read, understand, and maintain than function definitions.</p>
<blockquote>
<p><strong>Note</strong>: macros need to be defined and brought into scope before they are usable in a file, as opposed to functions that can be defined anywhere and be called anywhere.</p>
</blockquote>
<h2 id="declarative-macros-macro-by-example">Declarative Macros (Macro-by-Example)</h2>
<p>At their core, <strong>declarative macros</strong> allow to write something similar to a Rust match expression.</p>
<p>Macros compare a value to patterns that are associated with particular code: in this situation, the value is the literal Rust source code passed to the macro; the patterns are compared with the structure of that source code; and the code associated with each pattern, when matched, replaces the code passed to the macro. This all happens during compilation.</p>
<p>Declarative macros are defined using the <code>macro_rules!</code> construct.</p>
<p>Each macro has a <em>name</em>, and <em>one or more rules</em>.</p>
<p>Each rule has two parts: a <em>matcher</em>, describing the syntax that it matches, and a <em>transcriber</em>, describing the syntax that will replace a successfully matched invocation. Both the matcher and the transcriber must be surrounded by delimiters.<br />
Macros can expand to expressions, statements, items (including traits, impls, and foreign items), types, or patterns.</p>
<div class="highlight"><table class="highlighttable"><tr><th colspan="2" class="filename"><span class="filename">Rust</span></th></tr><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"><a href="#__codelineno-0-1">1</a></span>
<span class="normal"><a href="#__codelineno-0-2">2</a></span>
<span class="normal"><a href="#__codelineno-0-3">3</a></span>
<span class="normal"><a href="#__codelineno-0-4">4</a></span>
<span class="normal"><a href="#__codelineno-0-5">5</a></span>
<span class="normal"><a href="#__codelineno-0-6">6</a></span></pre></div></td><td class="code"><div><pre><span></span><code><a id="__codelineno-0-1" name="__codelineno-0-1"></a><span class="cp">#[macro_export]</span>
<a id="__codelineno-0-2" name="__codelineno-0-2"></a><span class="fm">macro_rules!</span><span class="w"> </span><span class="o">&lt;</span><span class="n">name</span><span class="o">&gt;</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-0-3" name="__codelineno-0-3"></a><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="o">&lt;</span><span class="n">matcher</span><span class="o">&gt;</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-0-4" name="__codelineno-0-4"></a><span class="w"> </span><span class="o">&lt;</span><span class="n">transcriber</span><span class="o">&gt;</span>
<a id="__codelineno-0-5" name="__codelineno-0-5"></a><span class="w"> </span><span class="p">};</span>
<a id="__codelineno-0-6" name="__codelineno-0-6"></a><span class="p">}</span>
</code></pre></div></td></tr></table></div>
<h3 id="transcribing">Transcribing</h3>
<p>When a macro is invoked, the macro expander looks up macro invocations by name, and tries each macro rule in turn. It transcribes the first successful match; if this results in an error, then future matches are not tried.</p>
<p>When matching, no lookahead is performed; if the compiler cannot unambiguously determine how to parse the macro invocation one token at a time, then it is an error.</p>
<p>In both the matcher and the transcriber, the <code>$</code> token is used to invoke special behaviours from the macro engine. Tokens that aren't part of such an invocation are matched and transcribed literally, with one exception.</p>
<p>The exception is that the outer delimiters for the matcher will match any pair of delimiters.<br />
Thus, for instance, the matcher (()) will match <code>{()}</code> but not <code>{{}}</code>.</p>
<blockquote>
<p><strong>Note</strong>: The character <code>$</code> cannot be matched or transcribed literally.</p>
</blockquote>
<p>When forwarding a matched fragment to another macro-by-example, matchers in the <em>second macro</em> will see an opaque AST of the fragment type. The second macro can't use literal tokens to match the fragments in the matcher, only a fragment specifier of the same type. The <code>ident</code>, <code>lifetime</code>, and <code>tt</code> fragment types are an exception, and can be matched by literal tokens.</p>
<div class="highlight"><table class="highlighttable"><tr><th colspan="2" class="filename"><span class="filename">Rust</span></th></tr><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"><a href="#__codelineno-1-1"> 1</a></span>
<span class="normal"><a href="#__codelineno-1-2"> 2</a></span>
<span class="normal"><a href="#__codelineno-1-3"> 3</a></span>
<span class="normal"><a href="#__codelineno-1-4"> 4</a></span>
<span class="normal"><a href="#__codelineno-1-5"> 5</a></span>
<span class="normal"><a href="#__codelineno-1-6"> 6</a></span>
<span class="normal"><a href="#__codelineno-1-7"> 7</a></span>
<span class="normal"><a href="#__codelineno-1-8"> 8</a></span>
<span class="normal"><a href="#__codelineno-1-9"> 9</a></span>
<span class="normal"><a href="#__codelineno-1-10">10</a></span>
<span class="normal"><a href="#__codelineno-1-11">11</a></span>
<span class="normal"><a href="#__codelineno-1-12">12</a></span></pre></div></td><td class="code"><div><pre><span></span><code><a id="__codelineno-1-1" name="__codelineno-1-1"></a><span class="fm">macro_rules!</span><span class="w"> </span><span class="n">foo</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-1-2" name="__codelineno-1-2"></a><span class="w"> </span><span class="p">(</span><span class="mi">3</span><span class="p">)</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{}</span>
<a id="__codelineno-1-3" name="__codelineno-1-3"></a><span class="p">}</span>
<a id="__codelineno-1-4" name="__codelineno-1-4"></a>
<a id="__codelineno-1-5" name="__codelineno-1-5"></a><span class="fm">macro_rules!</span><span class="w"> </span><span class="n">bar</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-1-6" name="__codelineno-1-6"></a><span class="w"> </span><span class="p">(</span><span class="cp">$l</span><span class="p">:</span><span class="nc">expr</span><span class="p">)</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">foo</span><span class="o">!</span><span class="p">(</span><span class="cp">$l</span><span class="p">);</span><span class="w"> </span><span class="p">}</span>
<a id="__codelineno-1-7" name="__codelineno-1-7"></a><span class="w"> </span><span class="c1">// ERROR: ^^ no rules expected this token in macro call</span>
<a id="__codelineno-1-8" name="__codelineno-1-8"></a><span class="p">}</span>
<a id="__codelineno-1-9" name="__codelineno-1-9"></a>
<a id="__codelineno-1-10" name="__codelineno-1-10"></a><span class="fm">macro_rules!</span><span class="w"> </span><span class="n">baz</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-1-11" name="__codelineno-1-11"></a><span class="w"> </span><span class="p">(</span><span class="cp">$l</span><span class="p">:</span><span class="nc">tt</span><span class="p">)</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">foo</span><span class="o">!</span><span class="p">(</span><span class="cp">$l</span><span class="p">);</span><span class="w"> </span><span class="p">}</span>
<a id="__codelineno-1-12" name="__codelineno-1-12"></a><span class="p">}</span>
</code></pre></div></td></tr></table></div>
<h3 id="metavariables"><a href="https://doc.rust-lang.org/reference/macros-by-example.html#metavariables">Metavariables</a></h3>
<p>In the matcher, <code>$name:fragment</code> matches a Rust syntax fragment of the kind specified and binds it to the metavariable <code>$name</code>.</p>
<p>Valid fragment specifiers are:</p>
<ul>
<li><code>item</code>: an <a href="https://doc.rust-lang.org/reference/items.html">Item</a></li>
<li><code>block</code>: a <a href="https://doc.rust-lang.org/reference/expressions/block-expr.html">BlockExpression</a></li>
<li><code>stmt</code>: a <a href="https://doc.rust-lang.org/reference/statements.html">Statement</a> without the trailing semicolon (except for item statements that require semicolons)</li>
<li><code>pat</code>: a <a href="https://doc.rust-lang.org/reference/patterns.html">Pattern</a></li>
<li><code>expr</code>: an <a href="https://doc.rust-lang.org/reference/expressions.html">Expression</a></li>
<li><code>ty</code>: a <a href="https://doc.rust-lang.org/reference/types.html#type-expressions">Type</a></li>
<li><code>ident</code>: an <a href="https://doc.rust-lang.org/reference/identifiers.html">IDENTIFIER_OR_KEYWORD</a> or <a href="https://doc.rust-lang.org/reference/identifiers.html">RAW_IDENTIFIER</a></li>
<li><code>path</code>: a <a href="https://doc.rust-lang.org/reference/paths.html#paths-in-types">TypePath</a> style path</li>
<li><code>tt</code>: a <a href="https://doc.rust-lang.org/reference/macros.html#macro-invocation">TokenTree</a> (a single token or tokens in matching delimiters <code>()</code>, <code>[]</code>, or <code>{}</code>)</li>
<li><code>meta</code>: an <a href="https://doc.rust-lang.org/reference/attributes.html">Attr</a>, the contents of an attribute</li>
<li><code>lifetime</code>: a <a href="https://doc.rust-lang.org/reference/visibility-and-privacy.html">LIFETIME_TOKEN</a></li>
<li><code>vis</code>: a possibly empty <a href="https://doc.rust-lang.org/reference/visibility-and-privacy.html">Visibility</a> qualifier</li>
<li><code>literal</code>: matches <a href="https://doc.rust-lang.org/reference/expressions/literal-expr.html">LiteralExpression</a></li>
</ul>
<p>In the transcriber, metavariables are referred to simply by <code>$name</code>, since the fragment kind is specified in the matcher. Metavariables are replaced with the syntax element that matched them.</p>
<p>The keyword metavariable <code>$crate</code> can be used to refer to the current crate. Metavariables can be transcribed more than once or not at all.</p>
<h3 id="repetitions">Repetitions</h3>
<p>In both the matcher and transcriber, repetitions are indicated by placing the tokens to be repeated inside <code>$(…)</code>, followed by a repetition operator, optionally with a separator token between. The separator token can be any token other than a delimiter or one of the repetition operators, but <code>;</code> and <code>,</code> are the most common.</p>
<p>The repetition operators are:</p>
<ul>
<li><code>*</code>: indicates any number of repetitions.</li>
<li><code>+</code>: indicates any number but at least one.</li>
<li><code>?</code>: indicates an optional fragment with zero or one occurrence.</li>
</ul>
<blockquote>
<p><strong>Note</strong>: Since <code>?</code> represents at most one occurrence, it cannot be used with a separator.</p>
</blockquote>
<p>The repeated fragment both matches and transcribes to the specified number of the fragment, separated by the separator token. Metavariables are matched to every repetition of their corresponding fragment.</p>
<p>During transcription, additional restrictions apply to repetitions so that the compiler knows how to expand them properly:</p>
<ol>
<li>A metavariable must appear in <em>exactly</em> the same number, kind, and nesting order of repetitions in the transcriber as it did in the matcher.</li>
<li>Each repetition in the transcriber must contain at least one metavariable to decide how many times to expand it. If multiple metavariables appear in the same repetition, they must be bound to the same number of fragments.</li>
</ol>
<h3 id="scoping-exporting-and-importing">Scoping, Exporting, and Importing</h3>
<p>Macros have two forms of scope: <em>textual scope</em>, and <em>path-based scope</em>. Textual scope is based on the order that things appear in source files, or even across multiple files, and is the default scoping. Path-based scope works exactly the same way that item scoping does. The scoping, exporting, and importing of macros is controlled largely by attributes.</p>
<p>When a macro is invoked by an unqualified identifier (not part of a multi-part path), it is first looked up in textual scoping. If this does not yield any results, then it is looked up in path-based scoping. If the macro's name is qualified with a path, then it is only looked up in path-based scoping.</p>
<div class="highlight"><table class="highlighttable"><tr><th colspan="2" class="filename"><span class="filename">Rust</span></th></tr><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"><a href="#__codelineno-2-1">1</a></span>
<span class="normal"><a href="#__codelineno-2-2">2</a></span>
<span class="normal"><a href="#__codelineno-2-3">3</a></span>
<span class="normal"><a href="#__codelineno-2-4">4</a></span>
<span class="normal"><a href="#__codelineno-2-5">5</a></span>
<span class="normal"><a href="#__codelineno-2-6">6</a></span>
<span class="normal"><a href="#__codelineno-2-7">7</a></span>
<span class="normal"><a href="#__codelineno-2-8">8</a></span>
<span class="normal"><a href="#__codelineno-2-9">9</a></span></pre></div></td><td class="code"><div><pre><span></span><code><a id="__codelineno-2-1" name="__codelineno-2-1"></a><span class="k">use</span><span class="w"> </span><span class="n">lazy_static</span><span class="p">::</span><span class="n">lazy_static</span><span class="p">;</span><span class="w"> </span><span class="c1">// path-based import.</span>
<a id="__codelineno-2-2" name="__codelineno-2-2"></a>
<a id="__codelineno-2-3" name="__codelineno-2-3"></a><span class="c1">// local textual definition.</span>
<a id="__codelineno-2-4" name="__codelineno-2-4"></a><span class="fm">macro_rules!</span><span class="w"> </span><span class="n">lazy_static</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-2-5" name="__codelineno-2-5"></a><span class="w"> </span><span class="p">(</span><span class="n">lazy</span><span class="p">)</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{};</span>
<a id="__codelineno-2-6" name="__codelineno-2-6"></a><span class="p">}</span>
<a id="__codelineno-2-7" name="__codelineno-2-7"></a>
<a id="__codelineno-2-8" name="__codelineno-2-8"></a><span class="n">lazy_static</span><span class="o">!</span><span class="p">{</span><span class="n">lazy</span><span class="p">}</span><span class="w"> </span><span class="c1">// textual lookup finds local macro first.</span>
<a id="__codelineno-2-9" name="__codelineno-2-9"></a><span class="bp">self</span><span class="p">::</span><span class="n">lazy_static</span><span class="o">!</span><span class="p">{}</span><span class="w"> </span><span class="c1">// path-based lookup ignores local macro, finds imported one.</span>
</code></pre></div></td></tr></table></div>
<blockquote>
<p><strong>Note</strong>: It is not an error to define a macro multiple times; the most recent declaration will shadow the previous one unless it has gone out of scope.</p>
</blockquote>
<h3 id="the-macro_use-attribute">The <code>macro_use</code> attribute</h3>
<p>The <code>macro_use</code> attribute has two purposes. First, it can be used to make a module's macro scope not end when the module is closed, by applying it to a module:</p>
<div class="highlight"><table class="highlighttable"><tr><th colspan="2" class="filename"><span class="filename">Rust</span></th></tr><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"><a href="#__codelineno-3-1">1</a></span>
<span class="normal"><a href="#__codelineno-3-2">2</a></span>
<span class="normal"><a href="#__codelineno-3-3">3</a></span>
<span class="normal"><a href="#__codelineno-3-4">4</a></span>
<span class="normal"><a href="#__codelineno-3-5">5</a></span>
<span class="normal"><a href="#__codelineno-3-6">6</a></span>
<span class="normal"><a href="#__codelineno-3-7">7</a></span>
<span class="normal"><a href="#__codelineno-3-8">8</a></span></pre></div></td><td class="code"><div><pre><span></span><code><a id="__codelineno-3-1" name="__codelineno-3-1"></a><span class="cp">#[macro_use]</span>
<a id="__codelineno-3-2" name="__codelineno-3-2"></a><span class="k">mod</span><span class="w"> </span><span class="nn">inner</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-3-3" name="__codelineno-3-3"></a><span class="w"> </span><span class="fm">macro_rules!</span><span class="w"> </span><span class="n">m</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-3-4" name="__codelineno-3-4"></a><span class="w"> </span><span class="p">()</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{};</span>
<a id="__codelineno-3-5" name="__codelineno-3-5"></a><span class="w"> </span><span class="p">}</span>
<a id="__codelineno-3-6" name="__codelineno-3-6"></a><span class="p">}</span>
<a id="__codelineno-3-7" name="__codelineno-3-7"></a>
<a id="__codelineno-3-8" name="__codelineno-3-8"></a><span class="n">m</span><span class="o">!</span><span class="p">();</span>
</code></pre></div></td></tr></table></div>
<p>Second, it can be used to import macros from another crate, by attaching it to an extern crate declaration appearing in the crate's root module. Macros imported this way are imported into the <code>macro_use</code> prelude, not textually, which means that they can be shadowed by any other name.</p>
<p>While macros imported by <code>#[macro_use]</code> can be used before the import statement, in case of a conflict, the last macro imported wins. Optionally, a list of macros to import can be specified using the <a href="https://doc.rust-lang.org/reference/attributes.html#meta-item-attribute-syntax"><code>MetaListIdents</code></a> syntax; this is not supported when <code>#[macro_use]</code> is applied to a module.</p>
<div class="highlight"><table class="highlighttable"><tr><th colspan="2" class="filename"><span class="filename">Rust</span></th></tr><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"><a href="#__codelineno-4-1">1</a></span>
<span class="normal"><a href="#__codelineno-4-2">2</a></span>
<span class="normal"><a href="#__codelineno-4-3">3</a></span>
<span class="normal"><a href="#__codelineno-4-4">4</a></span>
<span class="normal"><a href="#__codelineno-4-5">5</a></span></pre></div></td><td class="code"><div><pre><span></span><code><a id="__codelineno-4-1" name="__codelineno-4-1"></a><span class="p">#</span><span class="w"> </span><span class="p">[</span><span class="n">macro_use</span><span class="p">(</span><span class="n">lazy_static</span><span class="p">)]</span><span class="w"> </span><span class="c1">// or #[macro_use] to import all macros.</span>
<a id="__codelineno-4-2" name="__codelineno-4-2"></a><span class="k">extern</span><span class="w"> </span><span class="k">crate</span><span class="w"> </span><span class="n">lazy_static</span><span class="p">;</span>
<a id="__codelineno-4-3" name="__codelineno-4-3"></a>
<a id="__codelineno-4-4" name="__codelineno-4-4"></a><span class="n">lazy_static</span><span class="o">!</span><span class="p">{}</span>
<a id="__codelineno-4-5" name="__codelineno-4-5"></a><span class="bp">self</span><span class="p">::</span><span class="n">lazy_static</span><span class="o">!</span><span class="p">{}</span><span class="w"> </span><span class="c1">// Error: lazy_static is not defined in `self`</span>
</code></pre></div></td></tr></table></div>
<blockquote>
<p><strong>Note</strong>: Macros to be imported with <code>#[macro_use]</code> must be exported with <code>#[macro_export]</code>.</p>
</blockquote>
<h3 id="the-macro_export-attribute">The <code>macro_export</code> attribute</h3>
<p>By default, a macro has no path-based scope. However, if it has the <code>#[macro_export]</code> attribute, then it is declared in the crate root scope and can be referred to normally.</p>
<div class="highlight"><table class="highlighttable"><tr><th colspan="2" class="filename"><span class="filename">Rust</span></th></tr><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"><a href="#__codelineno-5-1"> 1</a></span>
<span class="normal"><a href="#__codelineno-5-2"> 2</a></span>
<span class="normal"><a href="#__codelineno-5-3"> 3</a></span>
<span class="normal"><a href="#__codelineno-5-4"> 4</a></span>
<span class="normal"><a href="#__codelineno-5-5"> 5</a></span>
<span class="normal"><a href="#__codelineno-5-6"> 6</a></span>
<span class="normal"><a href="#__codelineno-5-7"> 7</a></span>
<span class="normal"><a href="#__codelineno-5-8"> 8</a></span>
<span class="normal"><a href="#__codelineno-5-9"> 9</a></span>
<span class="normal"><a href="#__codelineno-5-10">10</a></span>
<span class="normal"><a href="#__codelineno-5-11">11</a></span>
<span class="normal"><a href="#__codelineno-5-12">12</a></span>
<span class="normal"><a href="#__codelineno-5-13">13</a></span>
<span class="normal"><a href="#__codelineno-5-14">14</a></span></pre></div></td><td class="code"><div><pre><span></span><code><a id="__codelineno-5-1" name="__codelineno-5-1"></a><span class="bp">self</span><span class="p">::</span><span class="n">m</span><span class="o">!</span><span class="p">();</span>
<a id="__codelineno-5-2" name="__codelineno-5-2"></a><span class="n">m</span><span class="o">!</span><span class="p">();</span><span class="w"> </span><span class="c1">// OK: Path-based lookup finds m in the current module.</span>
<a id="__codelineno-5-3" name="__codelineno-5-3"></a>
<a id="__codelineno-5-4" name="__codelineno-5-4"></a><span class="k">mod</span><span class="w"> </span><span class="nn">inner</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-5-5" name="__codelineno-5-5"></a><span class="w"> </span><span class="k">super</span><span class="p">::</span><span class="n">m</span><span class="o">!</span><span class="p">();</span>
<a id="__codelineno-5-6" name="__codelineno-5-6"></a><span class="w"> </span><span class="k">crate</span><span class="p">::</span><span class="n">m</span><span class="o">!</span><span class="p">();</span>
<a id="__codelineno-5-7" name="__codelineno-5-7"></a><span class="p">}</span>
<a id="__codelineno-5-8" name="__codelineno-5-8"></a>
<a id="__codelineno-5-9" name="__codelineno-5-9"></a><span class="k">mod</span><span class="w"> </span><span class="nn">mac</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-5-10" name="__codelineno-5-10"></a><span class="w"> </span><span class="cp">#[macro_export]</span>
<a id="__codelineno-5-11" name="__codelineno-5-11"></a><span class="w"> </span><span class="fm">macro_rules!</span><span class="w"> </span><span class="n">m</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-5-12" name="__codelineno-5-12"></a><span class="w"> </span><span class="p">()</span><span class="w"> </span><span class="o">=&gt;</span><span class="w"> </span><span class="p">{};</span>
<a id="__codelineno-5-13" name="__codelineno-5-13"></a><span class="w"> </span><span class="p">}</span>
<a id="__codelineno-5-14" name="__codelineno-5-14"></a><span class="p">}</span>
</code></pre></div></td></tr></table></div>
<blockquote>
<p><strong>Note</strong>: Macros labeled with <code>#[macro_export]</code> are always pub and can be referred to by other crates, either by path or by <code>#[macro_use]</code>.</p>
</blockquote>
<h3 id="follow-set-ambiguity-restrictions"><a href="https://doc.rust-lang.org/reference/macro-ambiguity.html">Follow-set Ambiguity Restrictions</a></h3>
<p>The parser used by the macro system is reasonably powerful, but it is limited in order to prevent ambiguity in current or future versions of the language.</p>
<p>In particular, in addition to the rule about ambiguous expansions, a nonterminal matched by a metavariable must be followed by a token which has been decided can be safely used after that kind of match.</p>
<p>The specific rules are:</p>
<ul>
<li><code>expr</code> and <code>stmt</code> may only be followed by one of: <code>=&gt;</code>, <code>,</code>, or <code>;</code>.</li>
<li><code>pat</code> may only be followed by one of: <code>=&gt;</code>, <code>,</code>, <code>=</code>, <code>if</code>, or <code>in</code>.</li>
<li><code>path</code> and <code>ty</code> may only be followed by one of: <code>=&gt;</code>, <code>,</code>, <code>=</code>, <code>|</code>, <code>;</code>, <code>:</code>, <code>&gt;</code>, <code>&gt;&gt;</code>, <code>[</code>, <code>{</code>, <code>as</code>, <code>where</code>, or a macro variable of block fragment specifier.</li>
<li><code>vis</code> may only be followed by one of: <code>,</code>, an identifier other than a non-raw priv, any token that can begin a type, or a metavariable with a <code>ident</code>, <code>ty</code>, or <code>path</code> fragment specifier.</li>
</ul>
<p>All other fragment specifiers have no restrictions.</p>
<p>When repetitions are involved, then the rules apply to every possible number of expansions, taking separators into account. This means:</p>
<ul>
<li>If the repetition includes a separator, that separator must be able to follow the contents of the repetition.</li>
<li>If the repetition can repeat multiple times (<code>*</code> or <code>+</code>), then the contents must be able to follow themselves.</li>
<li>The contents of the repetition must be able to follow whatever comes before, and whatever comes after must be able to follow the contents of the repetition.</li>
<li>If the repetition can match zero times (<code>*</code> or <code>?</code>), then whatever comes after must be able to follow whatever comes before.</li>
</ul>
</article>
</div>
<script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script>
</div>
<button type="button" class="md-top md-icon" data-md-component="top" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg>
Back to top
</button>
</main>
<footer class="md-footer">
<nav class="md-footer__inner md-grid" aria-label="Footer" >
<a href="rust.html" class="md-footer__link md-footer__link--prev" aria-label="Previous: Rust">
<div class="md-footer__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11z"/></svg>
</div>
<div class="md-footer__title">
<span class="md-footer__direction">
Previous
</span>
<div class="md-ellipsis">
Rust
</div>
</div>
</a>
<a href="cargo.html" class="md-footer__link md-footer__link--next" aria-label="Next: Cargo">
<div class="md-footer__title">
<span class="md-footer__direction">
Next
</span>
<div class="md-ellipsis">
Cargo
</div>
</div>
<div class="md-footer__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M4 11v2h12l-5.5 5.5 1.42 1.42L19.84 12l-7.92-7.92L10.5 5.5 16 11z"/></svg>
</div>
</a>
</nav>
<div class="md-footer-meta md-typeset">
<div class="md-footer-meta__inner md-grid">
<div class="md-copyright">
<div class="md-copyright__highlight">
MIT
</div>
Made with
<a href="https://squidfunk.github.io/mkdocs-material/" target="_blank" rel="noopener">
Material for MkDocs
</a>
</div>
<div class="md-social">
<a href="https://hachyderm.io/@m_lamonaca" target="_blank" rel="noopener me" title="hachyderm.io" class="md-social__link">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M433 179.11c0-97.2-63.71-125.7-63.71-125.7-62.52-28.7-228.56-28.4-290.48 0 0 0-63.72 28.5-63.72 125.7 0 115.7-6.6 259.4 105.63 289.1 40.51 10.7 75.32 13 103.33 11.4 50.81-2.8 79.32-18.1 79.32-18.1l-1.7-36.9s-36.31 11.4-77.12 10.1c-40.41-1.4-83-4.4-89.63-54a102.5 102.5 0 0 1-.9-13.9c85.63 20.9 158.65 9.1 178.75 6.7 56.12-6.7 105-41.3 111.23-72.9 9.8-49.8 9-121.5 9-121.5m-75.12 125.2h-46.63v-114.2c0-49.7-64-51.6-64 6.9v62.5h-46.33V197c0-58.5-64-56.6-64-6.9v114.2H90.19c0-122.1-5.2-147.9 18.41-175 25.9-28.9 79.82-30.8 103.83 6.1l11.6 19.5 11.6-19.5c24.11-37.1 78.12-34.8 103.83-6.1 23.71 27.3 18.4 53 18.4 175z"/></svg>
</a>
<a href="https://github.com/m-lamonaca" target="_blank" rel="noopener" title="github.com" class="md-social__link">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 496 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M165.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8M97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg>
</a>
</div>
</div>
</div>
</footer>
</div>
<div class="md-dialog" data-md-component="dialog">
<div class="md-dialog__inner md-typeset"></div>
</div>
<script id="__config" type="application/json">{"base": "../..", "features": ["navigation.instant", "navigation.indexes", "navigation.tracking", "navigation.pruning", "navigation.sections", "navigation.top", "navigation.tabs", "navigation.tabs.sticky", "navigation.footer", "toc.follow", "content.code.copy"], "search": "../../assets/javascripts/workers/search.07f07601.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}}</script>
<script src="../../assets/javascripts/bundle.56dfad97.min.js"></script>
</body>
</html>
Reference in a new issue View git blame Copy permalink